1. Field of the Invention
The present invention relates to an image forming apparatus and a control method therefor, and more particularly, to an image forming apparatus such as a copying machine or a printer for performing both-sided printing and a control method therefor.
2. Description of the Related Art
Conventionally, there has been a known printer for performing both-sided printing by inverting a sheet after finishing printing a first side of the sheet to print the second side thereof. Such a printer puts the inverted sheet on standby on a paper path in the case where, after finishing printing the first side, it cannot start printing the second side in predetermined timing for a reason such as delay in image development of an image to be formed on the second side. In many cases, such a printer has length of the paper path designed to be short for the sake of miniaturizing the printer, and a part of the sheet is thus exposed outside the printer on inverting-the sheet.
In the case where the printer cannot start printing the second side in the predetermined timing after finishing printing the first side, it puts the sheet on standby in a state of having a part of the sheet exposed outside the printer. For that reason, in the case where a sheet of a large size such as A3 size is put on standby in particular, the part of the sheet exposed outside the printer on standby is so large that a user may judge that a print job is finished and mistakenly pull out the sheet.
Thus, there is a proposed technique of passing a hold current through a motor for driving a roller holding the sheet tightly when putting the sheet on standby so as to prevent the roller from rotating in a direction of pullout (refer to Japanese Patent No. 3334481 for instance).
As for the technique described in Japanese Patent No. 3334481, however, the part of the sheet exposed outside the printer on standby is so large that the user cannot recognize the ongoing print job. To be more specific, it is not possible to prevent the user form pulling out the sheet on standby. For that reason, there are the cases where, as the user tires to pull out the sheet on standby after finishing printing the first side, an image forming position on the sheet becomes displaced from a proper position where the image should be formed and so the printing on the second side is not normally performed.